Method and apparatus for the production of music



Oct. 3, 1933. B. F. MIESSNER 1,929,023

METHOD AND APPARATUS FOR THE PRODUCTION OF MUSIC Original Filed Oct. 3,1951 IN V EN TOR:-

BY AT RNEY.

Patented Oct. 3, 1933 UNITED STATES PATENT OFFICE METHOD AND APPARATUSFOR THE PRODUCTION OF MUSIC Benjamin F.

Miessner, Mlllburn Township,

Application October 3, 1931, Serial No. 566,628 Renewed January 13, 193312 Claims.

This invention relates to the production of music through electric mediaand more specifically to mechanical and electrical methods and apparatusfor the control of such production. This application deals in part withimprovements on the methods and apparatus disclosed in my co-pendingapplication Serial Number 512,399, filed January 20, 1931.

It is an object of my invention to provide, in a musical instrument ofthe type wherein the vibrations of mechanical vibrators are successivelytranslated into electric oscillations and into sound, control means andmethods for selectively varying the quality, in respect of timbre, ofthe output tone or tones produced. Other and allied objects will morefully appear from the following description and the appended claims.

In the detailed description of my invention hereinafter set forth,reference is had to the accompanying drawing, of which:-

Figure l is a top view of a portion of a musical instrument embodyingcertain of the principles of my invention; and

Figure 2 is a cross-sectional view taken along line 2-2 in Figure l, inwhich certain electrical and electro-acoustic apparatus also embodied inmy invention appear schematically.

A simple embodimentof my invention may include tuned strings which maybe set into vibration, mechanico-electric apparatus for translating thevibrations of the strings into electric oscillations, an amplifier forsuch oscillations and a loudspeaker or other electro-acoustic apparatusfor translating the amplified oscillations into sound; and variouscontrol devices associated therewith, as hereinafter more fully appears.

Thus in Figure 1 I show a top view of a frame carrying a plurality oftuned strings, a simple action for selectively setting the strings intovibration and for damping the vibrations of the strings, and a key-boardfor operating such action. The frame may consist of a base 67 carryingon the bottom struts or longitudinal compression bars 68, back end bar69, front end bar 70 and pin piece 71. Tuning pins 65, equipped withlock nuts 66, may be screwed into both pin piece 71 and front end bar'70. Strings 61 may be secured to a tuning pin, passed through hole 64in front bar 70, thru a hole 81 in rear bar 69, and back throughadjacent holes 81 and 64 to the adjacent tuning pin, providing by asingle length of string two vibrators; a single length may of course beutilized for one vibrator if desired, it being secured at the back endbar after passing through hole 81. I have preferred to employ a framecarrying 24 strings so dimensioned that the length of the longest stringwill be between 3 and 4 times that of the shortest and that the distancebetween strings, measured perpendicularly thereto, will be the meansepaa ration between centers of adjacent keys on the keyboard. Plate 67may be provided with a row of holes 74, preferably at approximately ofeach string length away from the front end of that string; and I preferso to angle the end 65 pieces 69 and '10 with respect to the stringsthat the row of holes '74 will fall in a straight line perpendicular tothe strings. Another row of holes 73 may be provided a few inches nearerthe back of the frame than row of holes 74.

A vertical cross-sectional view of the instrument of Figure 1, takenalong a middle string, is shown as Figure 2. The frame may be supported,on base 91 by supports 92 and 93. Key 15 is shown rocking aboutvertical pin 76 on felt pad 50. The key may be counterweighted, so thatits front end is normally raised, by means of weight 7'7, and may beprovided with back stop 94 and with felt tipped block 19. Front lateralguide pin 95 may be used to hold the key in 39 lateral alignment. 4'?and 48 may be felt pieces for reducing noise produced by key motion.

' Rocker arm 9, pivoted as at 10 between supports 11 and equipped withweight 14 and hammer 8 is shown. A damper 72, of soft material such 35as felt, is provided at the rear end of the rocker arm, so that it restsnormally on string 61 through hole 73 in frame 67. When key 15 isdepressed as far as block 75 and felt 47 permit, rocker arm 9 is movedso that damper 72 is raised from string 61 and hammer 8 approaches thestring through hole 74. If the downward motion of the key be other thanextremely gradual, the momentum developed by rocker arm 9 causes hammer8 to strike the string, setting it into vibration.

When key 15 is released or allowed to rise again, damper 72 againcontacts with the string, stopping its vibration. Such a striking actionwill be seen to be touch-responsive, in that the amplitude of vibrationof the string depends on the mass per unit length, i. e., of similarwire, may 110 inversely be used throughout without necessitating largedepartures from a given tension in the cases of the different strings.For extending'the pitch range of the instrument downward I have found itconvenient to use another frame, which mayifdesiredbesimilartothatshownlnr'igurel but with front and back endpieces parallel and separated by the greatest string length in the frameof Figure 1, using wire of progressively larger mass per unit length forprogressively lower frequencies, and employing soft-ironwound music wirefor the lowest frequency vibrators.

Below each string may be employed a mechanico-electric translatingdevice, shown in Figures 1 and 2 as a bar magnet 97, supported as byblock 99, carrying near its upper extremity or pole a coil 98. Themagnet, the gap formed between its upper pole and the associated string,and the leakage paths from various portions of such string back to themagnet in general form a magnetic circuit threading the associated coil;and variations of the gap, produced by vibration of the string, vary thereluctance of this circuit and cause an A. C. voltage of fundamentalfrequency similar to that of the string, and of harmonic structuresubstantially similar to that of the vibration of the mean point of thestring opposite the magnet, to appear across the extremities of thecoil. The coils of the several translating devices may be connectedtogether, preferably in series; and A. C. voltages appearing across theextremities of any one will then appear across the extremities of thegroup or entire translating system, such extremities being shown aswires or leads 1 in both Figures 1 and 2.

It is well known that the vibration of a stretched string possesses notonly a fundamental frequency but also a large complement of harmonicfrequencies. While the amplitude of fundamental frequency vibration ofthe string is normally greatest at one spot, the center of the stringlongitudinally, the amplitude of any particular harmonic frequencyvibration is at'a maximum at a plurality of longitudinal positions,known as loops for that harmonic, and is at zero at others, known asnodes. At each point between the center of the string and one endthereof the ratios among themselves of the amplitudes of the vibrationsat the fundamental and various harmonic frequencies are different. Thusby associating a v mechanico-electric translating device selectivelywith various portions of the string between the center and one end it ispossible to vary the waveform of the outputof the translating de-,

vice and hence the timbre of the tone produced by this embodiment of myinvention. I therefore prefer to mount the translating devices so thattheir longitudinal positions with respect to the strings may be varied,as on block 99, which is provided with felt 46 and which may be moved toand fro along the strings by rod 38 passing through felt 39 in block 57and through felt 40 in block 92. The trough formed by base 91 and blocks92 and 93 may advantageously be lined with groundedmetal shield 45 forthe reduction of the sensitivity of the translating devices to strayelectrostatic and other fields.

The specific electromagnetic form oftranslatingsystemdisclosedwillbeseentobecbaracterlzed by sensitiveportions in spaced relationship to the strings and to operate inaccordance with vibratory variation of such spacing; it is directlyresponsive to oscillatory displacements ofactivepartsofthestrings.Idonotwish,

however, to limit the various features of my invention to use with suchtranslating devices, 1 since it will be apparent that other types oftranslating devices may be suitably arranged to carry out the basicprinciples herein disclosed. I In Figure 2 the leads 1, representing theelectrical extremities of the group of translating devices, will be seento be connected to the amplifier 41. Connected to the output ofamplifier 41 is shown tone control circuit 40, comprising for 315example potentiometer 21 and inductance 22 and capacity 23 andhereinafter more completely discussed; and volume control 42. This maybe followed if desired by further amplifier 43, to the output of whichmay be connected loudspeaker or other electro-acoustic translatingdevice 44. Thus A. C. voltages appearing across the leads 1 may beamplified, controlled both in respect of volume and of harmonicstructure as hereinafter more fully set forth, and translated intosound. 95 It will be understood, of course, that a single amplifier maybe employed in place of the two amplifiers 41 and 43; and that either orboth the tone control 40 and volume control 42 may precede or follow theentire amplifier, as desired.

The tone control 40 as shown comprises a potentiometer 21, preferablyhaving a total resistance of several times the output impedance ofamplifier 41, and an inductance 42 and condenser 43,

arranged so that the inductance and capacity are each shunted across theoutput of amplifier 41, each in series with a resistance the value ofwhich may be raised for one and simultaneously lowered for the other.When the movable contact of the potentiometer is in the centralposition, no sufiicient resistance is in series with each to makenegligible its effect as a shunt across the amplifier output. If,however, the movable contact of the potentiometer be moved toward eitherinductance 22 or capacity 23, that element will be made more effectiveas a shunt, and will attenuate low or high frequency components,respectively, of the omillations in the output of the amplifier. Thechoice of the values of inductance and capacity to be employed in aparticular case will depend on the associated circuit parameters,particularly the output impedance of the preceeding amplifier 41, and onthe maximum degree of low and high frequency attenuation which it isdesired to effect, as will be understood.

While the use of adjustable tone controls in association with electricalamplifiers is in general old, I hereinafter claim as my invention theuse of such a control with a musical instrument of the class described;and I have found that special and otherwise unattainable results may beachieved by its use. For example, it is well known that the relativeviolence of the percussion of a vibrator varies its mode of vibrationi.e., alters not only the absolute but also the relative amplitudes of thevarious partial components of its vibration. Thus in the instant examplehigh volumes of sound may be produced by violent percusion of the tunedvibrators, which at the same 14c time causes their vibration to containa relatively large complement of higher partials; and at the same timethis high volume of output tones may be accompanied by a harmonicstructure of such tones relatively weak in higher partial components,due to an adjustment of the tone control 40 to attenuate the-higherfrequencies. It willbeimderstoodthatavarietyofforms oftone control 40may be employed, it being intended to illustrate a devieewhereby therelative ampli- 15p tudes of componmts of the electric oscillations maybe controlled on an absolute frequency basis. This result dilfers fromthat produced by motion of translating devices along the strings, aseffected by rod 38, in that the latter effects a control on the basis,not of absolute frequency, but of particular partial components of thevibration of each vibrator.

The stringed instrument disclosed will be seen to be basically a piano,in which the strings are otherwise than customarily supported, in whicha simplified action is employed, and in which no soundboard or otherresonator is employed; the vibrations of the strings being translated,instead of directly into sound waves, into electric oscillations andthese in turn into sound waves. The substitution of these mesnevibration-oscillation (mechanico-electric) and oscillation-sound(electro-acoustic) translations for the conventional directvibration-sound (mechanico-acoustic) translation, as distinguished fromtheir simple addition to such direct translation, results in substantialcompleteness of control over the output sound in respect of itsamplitude-i. e., that effected by potentiometer 42-and of controlthereover in respect of quality-e. g., the controls over timbre effectedby the positioning of rod 38 and block 46 and by the adjustment of thetone control circuit 40.

It will be understood that the various control devices comprising myinvention are capable of employment with wide' modifications of theapparatus shown, without departure from the spirit or scope of myinvention. Thus for example other forms of vibrators than strings may beemployed; other methods than key-actuated percussion used for vibratingthe vibrators; other forms of mechanico-electric translating devicesthan the magnet and coil assemblies may be employed; a singletranslating device may be used in association with all or a group of thevibrators, thus reducing the required number of such devices; etc.

I claim:-

1. The method of producing musical tones from a tuned vibrator and ofcontrolling their timbre, which comprises vibrating said vibrator at aplurality of its partial frequencies, translating the vibration of saidvibrator into electric oscillations, selectively controlling therelative amplitudes of components of said oscillations on the basis ofparticular partials of said vibration of said vibrator, and selectivelycontrolling the relative amplitudes of components of said oscillationson the basis of the absolute frequencies thereof.

2. The method of producing musical tones from a tuned vibrator and ofcontrolling their timbre, which consists in producing complex mechanicaloscillations of said vibrator comprising a plurality of harmonicallyrelated partial components, in translating said complex oscillationsfrom said mechanical into an acoustic form substantially entirely bymesne translations thereof first into the form of complex electricoscillations and thence into the form of sound, and in selectivelycontrolling the relative amplitudes of the various said partialoscillation components intermediately of said two translations.

3. In the production of musical tones from the mechanical vibration ofa-single vibrator, which vibration is characterized by componentvibrations of a plurality of predetermined frequencies producing aresultant complex vibration, the method of timbre control whichcomprises translating said complex mechanical vibration into electricoscillations, controlling said translation selectively with respect tovarious of said component vibrations, and thereafter selectivelycontrolling the relative amplitudes of the various frequency componentsof the electric oscillations produced by said translation.

4. The method of producing musical tones from a tuned vibrator and ofcontrolling their timbre, which consists in producing complex mechanicaloscillations of said vibrator comprising a plurality of harmonicallyrelated components, in translating said complex oscillations from saidmechanical into an acoustic form substantially entirely by mesnetranslations thereof first into the form of complex electricoscillations and thence into the form of sound, in controlling the firstof said mesne translations selectively with respect to various of saidpartial components, and in selectively controlling the relativeamplitudes of the various said partial oscillation componentsintermediately of said two translations.

5. In the production of music from a plurality of selectively operatedsources of electric oscillations of respectively different fundamentalfrequencies, the oscillations from each source comprising a plurality ofharmonically related partial components, the method of timbre controlwhich comprises selectively controlling the energy distribution betweenvarious of the said partial component oscillations from each source,combining the oscillations from the several sources, and selectivelycontrollin the relative amplitudes of different frequency components ofsaid combined oscillations.

6. A musical instrument wherein substantially the entire output sound istranslated from electric oscillations, comprising an electro-acoustictranslating device for effecting such translation; a plurality ofvariously tuned vibrators; means selective with respect to saidvibrators for producing in each vibrations having a plurality ofharmonically related partial components; a mechanico-electrictranslating system associated with said vibrators and operative totranslate said vibrations thereof into electric oscillations; means fortransmitting said oscillations to said electro-acoustic translatingdevice; and means included in said transmitting means for selectivelyvarying the relative amplitudes of different frequency components ofsaid oscillations.

7. A musical instrument wherein substantially the entire output sound istranslated from electric oscillations, comprising an electro acoustictranslating device for eifecting such translation; a plurality ofvariously tuned vibrators; means selective with respect to saidvibrators for producing in each vibrations having a plurality ofharmonically related partial components; a mechanico-electrictranslating system associated with said vibrators and operative totranslate said vibrations thereof into electric oscillations; and meansfor transmitting said oscillations to said electro-acoustic translatingdevice, said means including a reactive circuit containing a resistanceelement selectively adjustable to vary the relative amplitudes ofdifferent frequency components of said oscillations.

8. A musical instrument comprising a plurality of variously tunedvibrators; means selective with respect to said vibrators for producingin each vibrations having a plurality of harmonically related partialcomponents; a mechanico-electric translating system associated with saidvibrators and operative to translate said vibrations thereof intoelectric oscillations; an electro-acoustic oscillations, comprising aplurality of variously tuned vibrators; means selective with respect tosaid vibrators for producing in each vibrations having a plurality ofharmonically related partial components; a mechanico-electrictranslating system associated with-said vibrators and operative totranslate said vibrations thereof into said first mentioned electricoscillations; means following said translating system for selectivelyvarying the relative amplitudes of different frequency components ofsaid oscillations; and

means included in said translating system for selectively controllingthe harmonic structure of the said oscillations translated from eachsaid vibrator.

10. A musical instrument wherein substantially the entire output soundis translated from electric oscillations, comprising a plurality ofvariously tuned vibrators; means selective with respect to saidvibrators for producing in each vibrations having a plurality ofharmonically related partial components; a mechanico-electrictranslating system having sensitive portions respectively in spacedrelationship to said vibrators, said system being operative to translatesaid vibrations into said first mentioned oscillations and beingselective in such operation with respect to said various partialcomponents of the vibration of each vibrator; means following saidtranslating system for selectively varying the relative amplitudes ofdif ferent frequency components of said oscillations; and means includedin said translating system for altering at will its said selectivitywith respect to partial components.

11. A piano comprising a plurality of variously tuned strings; hammersrespectively associated therewith and each operable at differentvelocities to produce in the therewith associated said string a complexvibration having partial frequency components of relative amplitudesdependent on hammer velocity; a mechanico-electric translating systemassociated with said strings and operative totranslate said vibrationsthereof into electric oscillations; an electro-acoustic translatingdevice; means for transmitting said oscillations to saidelectro-acoustic translating device; and means included in saidtransmitting means for selectively varying the relative amplitudes ofdiiferent frequency components of said oscillations.

I 12. A piano wherein substantially the entire sound output istranslated from electric oscillations, comprising an electro-acoustictranslating device for effecting such translation; a plurality ofvariously tuned strings; hammers respectively associated therewith andeach operable at different velocities to produce in the therewithassociated said string a complex vibration having partial frequencycomponents of relative amplitudes dependent on hammer velocity; amechanicoelectric translating system associated with said strings andoperative to translate said vibrations thereof into electricoscillations; means for transmitting said oscillations to saidelectro-acoustic translating device; and means included in saidtransmitting means for selectively varying the relative amplitudes ofdifferent frequency components of said oscillations.

BENJAMIN F. MIESSNER.

